Many of us would be relieved if God had place dour sanctification in the hands of trained professionals, but that simply is not the biblical model. God’s plan is that through the faithful ministry of every part, the whole body will grow to maturity in Christ.
Tripp explains how his work follows an "all of my people, all of the time" model. If you followed the Lord for a thousand years, you would still need the ministry of the body of Christ as much as you did the day you first believed. This need will remain until our sanctification is complete in Glory.
This is a comprehensive treatment of how God uses people as tools of change in the lives of others, people who themselves are in need of change.